This invention relates to a direction changing device for leading the direction of extending a bioptic instrument such as forceps to an aimed position in the field of vision for observation.
As is well known in the art, an endoscope such as a gastroscope or a bronchoscope comprises an optical system for observing a portion of the body, a bioptic instrument such as forceps for taking a sample from the body and other auxiliary devices such as for instance a device for supplying and discharging water or air. Accordingly, passages for these devices are incorporated in a flexible pipe extending from the portion of the body to be examined to the manual operating section of the endoscope. Opening and working sections for these devices are arranged in the top portion of the flexible pipe, which reaches the portion of the body to be examined.
For instance, the objective lens of an observing optical system, especially the viewing optical system and the opening of the passage for the bioptic instrument are juxtaposed in the end face of the flexible tube. Therefore, the functioning ranges, that is, the field of vision of the optical system and the region of a portion of the body to be examined to which the bioptic instrument can extend, of these devices are not in coincidence with one other. Thus, taking a sample from the portion of the body under examination in the periphery of the field of vision for observation is sometimes outside the range of the bioptic instrument, which makes it difficult to perform such operation.
Recently, a variety of devices have been proposed for allowing the working region of the bioptic instrument to approach the central region of the field of vision for observation. For instance, a device has been proposed in which an operating section is incorporated in the end portion of a flexible pipe. The operating section functions to incline the field of vision of the observing optical system towards the side of extension of the bioptic instrument with respect to the end face of the flexible tube and to deflect the pipe of the bioptic instrument to a plane which crosses the field of vision. The concept is disclosed in Japanese Utility Model Laid-Open No. 20489/1975.
A conventional technique of changing the direction of the end portion of the pipe of a bioptic instrument is disclosed by Japanese Utility Model Laid-Open Nos. 20489/1975 and 22694/1975 and Japanese Utility Model Application Publication No. 53789/1976. In these systems an operating pipe into which the pipe of the bioptic instrument is inserted is provided in the end portion of the flexible pipe and the operating pipe is deflected manually to change the direction of the pipe of the bioptic instrument.
A conventional direction changing device of this type is incorporated in the metal part provided at the end portion of the flexible tube, and therefore a larger part of the end portion of the flexible tube is occupied by the device. Accordingly, devices incorporated in the flexible tube, i.e., devices built in the endoscope are limited. Furthermore, the field of vision of the observing optical system is apt to be narrowed by the shape of the direction changing device. In addition, the conventional direction changing device is disadvantageous in that it is impossible to increase the direction changing angle.